A method for targeted recycling of waste batteries

Abstract

The application provides a method for targeted recycling of waste batteries, which comprises the following steps: crushing the positive electrode strip of the waste battery to obtain a crushing product; pyrolyzing the crushing product in a carbon monoxide atmosphere to obtain a pyrolysis product, and then performing magnetic separation on the pyrolysis product to obtain a magnetic separation product to realize recovery of valuable metals; and passing the pyrolysis gas of the pyrolysis into an alkaline solution to obtain a lithium-rich solution to realize recovery of lithium. The method can induce directional transfer of solid-state oxygen in the waste positive electrode material through pyrolysis, form a coexisting environment of cobalt single substance and aluminum oxide, effectively inhibit high-temperature alloying, utilize high-temperature complexing reaction of carbon monoxide and newly formed cobalt single substance, induce cobalt nanoparticles to target and gather to form millimeter-level large particles against the carbon monoxide concentration gradient, so as to realize magnetic separation and recovery, and the method can realize industrial application.

Description

Technical Field

[0001] This invention belongs to the field of pyrometallurgy or waste lithium battery resource recycling technology, and relates to a method for targeted recycling of waste batteries. Background Technology

[0002] Currently, electrification in the transportation sector is considered a crucial measure to effectively reduce carbon emissions and combat global warming. Lithium-ion batteries are key components of electric vehicles, providing some or all of their power output. However, lithium-ion batteries have a limited cycle life and require rapid replacement, resulting in a large number of retired power batteries being generated annually.

[0003] With the rapid depletion of global strategic mineral resources such as lithium and cobalt, the deep recycling of valuable metals from retired power batteries will significantly extend their life cycle. Currently, the recycling of waste lithium batteries is mainly based on metallurgical chemical technologies, and it is estimated that 90% of the world's waste lithium batteries will enter hydrometallurgical and pyrometallurgical systems for recycling. Compared with hydrometallurgical recycling, pyrometallurgical technology has advantages such as a shorter process, simpler and more reliable equipment, lower operating costs, and no wastewater discharge, making it the main recycling technology route for existing recycling companies.

[0004] CN 109719117A discloses a pyrolysis method for recycling waste lithium batteries. The method involves wrapping the de-cased waste battery cells with a mixture of fire extinguishing sand and conductive carbon black. The wrapped cells are then placed in a sealed container and purged with carbon dioxide or a carbon dioxide-containing gas mixture, or under vacuum. The sealed container is then placed in a microwave oven and heated for 5-500 seconds using a combination of microwave and light wave heating. After cooling, the cells are removed, crushed, and sieved to obtain electrode material powder and copper-aluminum foil. This method provides a carbothermic reduction roasting method using conductive carbon black as a reducing agent, and further improves thermal efficiency through a combination of microwave and light wave heating. The final products are electrode material powder and copper-aluminum foil.

[0005] CN 111834683A discloses a method for recycling waste lithium cobalt oxide batteries. Step 1 involves biomass pyrolysis of the waste lithium cobalt oxide batteries to obtain a mixture of cobalt powder and lithium oxide. Step 2 involves crushing and sorting the mixture from Step 1 to obtain plastic, iron, aluminum foil, copper foil, and positive and negative electrode powders. Step 3 involves slurrying and washing the positive and negative electrode powders from Step 2, followed by filtration to obtain a lithium hydroxide solution and carbon-containing cobalt powder. Step 4 involves reacting the lithium hydroxide solution from Step 3 with hydrochloric acid. The reaction yields lithium chloride; the carbon-containing cobalt powder from step 3 is mixed and reacted with sulfuric acid, then concentrated and crystallized to obtain cobalt sulfate crystals, thus completing the recycling of waste lithium cobalt oxide batteries; this provides a method for biomass pyrolysis of waste lithium cobalt oxide batteries to obtain a mixture of cobalt powder and lithium oxide; that is, after crushing and sorting the mixture, plastic, iron, aluminum foil, copper foil and positive and negative electrode powders are obtained; the positive and negative electrode powders are subjected to slurry washing, hydrochloric acid reaction and sulfuric acid leaching to obtain lithium chloride and cobalt sulfate stepwise.

[0006] CN 109652654A discloses a method for resource recovery of metal elements from waste ternary lithium-ion batteries. The method involves immersing the crushed waste lithium-ion battery products in water and then subjecting them to high-temperature pyrolysis in a CO2 atmosphere. The pyrolysis products are then subjected to acid leaching, extraction, and ammonia complexation to prepare ternary composite hydroxides.

[0007] However, all of the above methods employ pyrolysis to volatilize and remove the electrolyte, and further utilize the inherent organic impurities of waste lithium batteries as a carbon source, or introduce CO2 gas to achieve the reduction and degradation of the transition metal oxide cathode material of waste lithium batteries through the carbothermic reduction principle. However, the lithium-aluminum-transition metal elements in the pyrolysis products of waste lithium batteries are complexly embedded and have tight atomic bonds, making it difficult to meet the quality requirements of primary industrial raw materials. Wet acid leaching, dissolution, separation, and purification are still required, resulting in low economic efficiency.

[0008] Based on the above research, there is a need to provide a method for targeted recycling of waste batteries. This method has a short process, low cost, can be industrially applied, and can achieve targeted separation of multiple metals. Summary of the Invention

[0009] The purpose of this invention is to provide a method for targeted recycling of waste batteries. The method induces the directional transfer of solid oxygen in waste cathode materials through pyrolysis, forming a coexistence environment of cobalt and alumina, which effectively inhibits high-temperature alloying. At the same time, it utilizes the high-temperature complexation reaction between carbon monoxide and newly formed cobalt to induce cobalt nanoparticles to aggregate against the carbon monoxide concentration gradient, forming millimeter-sized large particles, thereby achieving magnetic separation and recycling. Moreover, the method of this invention can be industrialized.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] This invention provides a method for targeted recycling of waste batteries, the method comprising the following steps:

[0012] (1) The positive electrode strip of the waste battery is crushed to obtain the crushed product;

[0013] (2) Under a carbon monoxide atmosphere, the crushed product described in step (1) is pyrolyzed to obtain a pyrolysis product. Then, the pyrolysis product is magnetically separated to obtain a magnetically separated product, thereby realizing the recovery of valuable metals.

[0014] (3) The pyrolysis gas from step (2) is passed into an alkaline solution to obtain a lithium-rich solution, thereby achieving lithium recovery.

[0015] Because cobalt nanoparticles, under specific conditions, can move and traverse the surface and interior of aluminum-based materials, and collide and aggregate into large particles in a carbon monoxide atmosphere, this invention proposes, based on the targeting principle, to induce carbon monoxide complexation in cobalt nanoparticles generated from the pyrolysis of waste lithium battery cathode strips by creating a carbon monoxide concentration difference inside and outside the sample. These nanoparticles then move against the carbon monoxide concentration gradient and aggregate into millimeter-sized large particles, thereby suppressing high-temperature alloying of mixed metals and achieving targeted separation of alloys such as aluminum and cobalt.

[0016] Furthermore, this invention utilizes the inherent positive electrode current collector of waste lithium batteries as a reducing agent (such as aluminum foil) to in-situ stimulate the aluminum foil reduction reaction of the positive electrode material, resulting in an aluminothermic reaction rather than a carbothermic reaction. Utilizing the principle of pyrolysis, it promotes interphase transfer of solid oxygen to form an environment where cobalt and aluminum oxide coexist, effectively suppressing high-temperature alloying. Specifically, based on the aluminum-cobalt-oxygen three-phase equilibrium principle, the only stable phase in which these three elements coexist is Al2CoO4, which requires a large amount of oxygen. However, this application is carried out in a carbon monoxide atmosphere, so stable Al2CoO4 will not form. On the other hand, the atmosphere in this application does not provide gaseous oxygen, but the positive electrode material phase contains a large amount of solid oxygen, so there is no absolutely oxygen-free environment, and cobalt cannot form pure metallic alloys such as AlCo, Al5Co2, and Al9Co2. Therefore, this invention utilizes the characteristic of waste lithium batteries carrying solid oxygen to achieve the separation of aluminum, cobalt, and other metallic phases through pyrolysis technology, laying a theoretical foundation for magnetic separation and recycling in subsequent steps.

[0017] This invention employs a carbon monoxide atmosphere for pyrolysis. Carbon monoxide does not contribute to reduction; it merely acts as a gas-phase complexing agent for newly formed transition metal elements. Based on the Elingham diagram of Gibbs free energies for different metal oxidation reactions, it can be observed that aluminum's strong reducing properties allow its oxidation reaction to proceed preferentially, thereby robbing oxygen from almost all metal oxides except Mg and Ca. That is, current collectors such as aluminum foil can reduce various metals, including nickel, cobalt, manganese, and iron, to their elemental forms through displacement reactions. More importantly, the minimum oxygen partial pressure (~10⁻²⁰ Pa) required for C and CO oxidation reactions is much greater than that required for aluminum oxidation (~10⁻⁴⁵ Pa). This indicates that the aluminothermic reduction reaction is far more effective at robbing oxygen than the carbothermic reduction reaction, proving that the CO atmosphere in this reaction does not contribute to reduction but only facilitates the formation of complexes of newly formed transition metal elements.

[0018] Preferably, in the carbon monoxide atmosphere described in step (2), the pressure of carbon monoxide is 10-800 Pa, for example, it can be 10 Pa, 50 Pa, 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa or 800 Pa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 100-500 Pa.

[0019] Preferably, the carbon monoxide atmosphere in step (2) is a low-vacuum carbon monoxide atmosphere, which is formed by introducing carbon monoxide at 10-800 Pa under vacuum conditions.

[0020] The gas pressure of carbon monoxide described in this invention affects the pyrolysis effect. Since carbon monoxide acts as a gaseous complexing agent, if its content is too low, the complexing effect decreases; if the carbon monoxide content is too high, a low vacuum environment cannot be formed, thus affecting the vacuum pyrolysis effect. Therefore, the carbon monoxide atmosphere described in this invention contains only a small amount of carbon monoxide gas to ensure low vacuum conditions. The chemical reaction is carried out in a low-vacuum, high-temperature carbon monoxide environment, where carbon monoxide induces the formation of Co(CO) from newly formed cobalt nanoparticles. n Metal complexes should be used to avoid the formation of stable Al2CoO4 compounds, while also preventing the formation of metal alloys without oxygen.

[0021] Preferably, in the carbon monoxide atmosphere described in step (2), the source of carbon monoxide gas includes pyrolysis gas from biomass.

[0022] Preferably, the biomass includes any one or a combination of at least two of wood chips, household waste, or garden waste.

[0023] Preferably, the reducing agent in step (2) for pyrolysis includes the current collector of the positive electrode strip.

[0024] Preferably, the current collector is aluminum foil.

[0025] This invention uses aluminum foil as the positive electrode strip for the positive current collector, so that the aluminum foil acts as a reducing agent to carry out the aluminothermic reaction and reduce other metals to elemental metals.

[0026] Preferably, the complexing agent used in step (2) for pyrolysis includes carbon monoxide.

[0027] Preferably, the pyrolysis in step (2) includes heating to a first temperature once, then heating to a second temperature twice, and finally cooling down.

[0028] Preferably, the first temperature is 400-600℃, for example, it can be 400℃, 450℃, 500℃, 550℃ or 600℃, and the holding time at the first temperature is 20-40min, for example, it can be 20min, 30min or 40min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] Preferably, the heating rate for a single heating step is 15-25℃ / min, for example, it can be 15℃ / min, 20℃ / min or 25℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the second temperature is 700-900℃, for example, 700℃, 800℃ or 900℃, and the holding time at the second temperature is 50-70min, for example, 50min, 60min or 70min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the heating rate of the secondary heating is 5-15℃ / min, for example, it can be 5℃ / min, 8℃ / min, 10℃ / min or 15℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the temperature drop to 20-35°C can be, for example, 23°C, 25°C, 30°C or 35°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the magnetic separation product in step (2) includes magnetically separated cobalt powder and non-magnetically separated lithium aluminate.

[0034] Preferably, the alkaline solution in step (3) includes a calcium hydroxide solution.

[0035] Preferably, the lithium concentration in the lithium-rich solution in step (3) is 5-10 g / L, for example, it can be 5 g / L, 7.5 g / L, 9.5 g / L or 10 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, in step (1), the waste battery is first physically short-circuited and discharged, then immersed in a salt solution for discharge, and finally dried and disassembled to obtain a positive electrode strip.

[0037] Preferably, the crushing method in step (1) includes shear crushing.

[0038] Preferably, the waste batteries in step (1) include waste lithium cobalt oxide batteries.

[0039] As a preferred embodiment of the present invention, the method includes the following steps:

[0040] (1) First, physically short-circuit and discharge the waste battery, then immerse it in a salt solution for discharge, and finally dry and disassemble it to obtain a positive electrode strip. Then, cut and crush the positive electrode strip to obtain the crushed product.

[0041] (2) Under vacuum conditions, carbon monoxide at 10-800 Pa is introduced to form a low vacuum carbon monoxide atmosphere. Under the low vacuum carbon monoxide atmosphere, the crushed product in step (1) is heated to 400-600℃ at a heating rate of 15-25℃ / min, held for 20-40 min, and then heated to 700-900℃ at a heating rate of 5-15℃ / min, held for 50-70 min, and then cooled to 20-35℃ to complete the pyrolysis and obtain the pyrolysis product.

[0042] (3) The pyrolysis product described in step (2) is subjected to magnetic separation to obtain magnetically separated cobalt powder and non-magnetically separated lithium aluminate;

[0043] (4) Pass the pyrolysis gas from step (2) into a calcium hydroxide solution to obtain a lithium-rich solution with a lithium concentration of 5-10 g / L.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention employs carbon monoxide atmosphere pyrolysis to create a carbon monoxide concentration difference inside and outside the sample, inducing the nanoparticles generated by the pyrolysis of waste lithium battery cathode strips to undergo carbon monoxide complexation and move against the carbon monoxide concentration gradient to aggregate into large millimeter-sized particles. This inhibits the high-temperature alloying of mixed metals and achieves targeted separation of alloys such as aluminum and cobalt. Furthermore, the method described in this invention can be applied industrially. Attached Figure Description

[0046] Figure 1 This is a flowchart of the method described in Embodiment 1 of the present invention;

[0047] Figure 2 This is a scanning electron microscope image of the movement of cobalt metal nanoparticles during the pyrolysis process described in Example 1 of the present invention.

[0048] Figure 3 This is an optical effect diagram of the positive electrode strip before pyrolysis as described in Embodiment 1 of the present invention;

[0049] Figure 4 This is an optical effect diagram of the targeted aggregation of cobalt metal nanoparticles after pyrolysis as described in Example 1 of the present invention. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] Example 1

[0052] This embodiment provides a method for targeted recycling of waste batteries, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0053] (1) In order to ensure the safety of the experimental process, the waste lithium batteries were safely discharged. Specifically, 100 waste lithium cobalt oxide mobile phone lithium batteries weighing about 2.5 kg were first discharged by physical short circuit for 12 hours, then immersed in 5% NaCl salt solution for full discharge for 48 hours, and then dried in a fume hood for 48 hours.

[0054] (2) The block-shaped waste lithium batteries after discharge were manually disassembled in a fume hood, and 100 waste positive electrode strips were removed.

[0055] (3) The discharged waste lithium battery positive electrode strips were sheared and crushed to obtain 1600g of crushed products;

[0056] (4) Under vacuum conditions, 200 Pa of carbon monoxide is introduced to form a low vacuum carbon monoxide atmosphere. In the pyrolysis furnace under the low vacuum carbon monoxide atmosphere, the crushed product in step (3) is heated to 500°C at a heating rate of 20°C / min, held for 30 min, and then heated to 800°C at a heating rate of 10°C / min. After holding for 60 min, the product is cooled to 25°C by auto-ignition to complete the low vacuum pyrolysis of carbon monoxide and obtain the pyrolysis product.

[0057] (5) The pyrolysis product described in step (4) is subjected to magnetic separation to obtain magnetically separated cobalt powder and non-magnetically separated lithium aluminate;

[0058] (6) The pyrolysis gas from the pyrolysis in step (4) is passed into a 1 mol / L calcium hydroxide solution to obtain a lithium-rich solution, wherein the lithium-rich solution is a lithium hydroxide-rich solution.

[0059] Scanning electron microscope (SEM) images of the movement of cobalt metal nanoparticles during the pyrolysis process described in this invention are as follows: Figure 2 As shown, the optical effect diagram of the positive electrode strip before pyrolysis is as follows: Figure 3As shown in the figure, the optical effect of targeted aggregation of cobalt metal nanoparticles after pyrolysis is as follows. Figure 4 As shown.

[0060] The present invention conducted multiple parallel experiments on Example 1 as follows, and the experimental results are as follows:

[0061] 1) Laboratory targeted pyrolysis experiment group A: The cobalt recovery rate in the cobalt powder product was 96.8%, the cobalt powder purity was 98.4%, the lithium aluminate product purity was 95.5%, and the lithium concentration in the lithium-rich solution was 6.3 g / L;

[0062] 2) Laboratory targeted pyrolysis experiment group B: The cobalt recovery rate in the cobalt powder product was 97.5%, the cobalt powder purity was 99.0%, the lithium aluminate product purity was 95.6%, and the lithium concentration in the lithium-rich solution was 5.8 g / L;

[0063] 3) Laboratory targeted pyrolysis experiment group C: The cobalt recovery rate in the cobalt powder product was 98.3%, the cobalt powder purity was 97.2%, the lithium aluminate product purity was 94.1%, and the lithium concentration in the lithium-rich solution was 7.1 g / L;

[0064] 4) Laboratory targeted pyrolysis experiment group D: The cobalt recovery rate in the cobalt powder product was 94.8%, the cobalt powder purity was 98.8%, the lithium aluminate product purity was 97.5%, and the lithium concentration in the lithium-rich solution was 8.3 g / L;

[0065] 5) Industrial-scale targeted pyrolysis pilot test group A: The cobalt recovery rate in the cobalt powder product was 92.4%, the cobalt powder purity was 94.7%, the lithium aluminate product purity was 93.7%, and the lithium concentration in the lithium-rich solution was 5.5 g / L;

[0066] 6) Industrial-scale targeted pyrolysis pilot test group A: The cobalt recovery rate in the cobalt powder product was 91.9%, the cobalt powder purity was 95.2%, the lithium aluminate product purity was 96.5%, and the lithium concentration in the lithium-rich solution was 3.9 g / L;

[0067] 7) Industrial-scale targeted pyrolysis pilot test group A: The cobalt recovery rate in the cobalt powder product was 94.8%, the cobalt powder purity was 95.8%, the lithium aluminate product purity was 92.7%, and the lithium concentration in the lithium-rich solution was 7.1 g / L;

[0068] 8) Industrial-scale targeted pyrolysis pilot test group A: The cobalt recovery rate in the cobalt powder product was 93.3%, the cobalt powder purity was 96.7%, the lithium aluminate product purity was 95.5%, and the lithium concentration in the lithium-rich solution was 5.5 g / L.

[0069] The above results show that the method described in this invention has excellent recycling effect, high stability of recycling effect, and can be applied industrially.

[0070] Example 2

[0071] This embodiment provides a method for targeted recycling of waste batteries, the method comprising the following steps:

[0072] (1) In order to ensure the safety of the experimental process, 100 waste lithium cobalt oxide mobile phone lithium batteries weighing about 2.5 kg were first discharged by physical short circuit for 12 hours, then immersed in 5% NaCl salt solution for full discharge for 48 hours, and then dried in a fume hood for 48 hours.

[0073] (2) The block-shaped waste lithium batteries after discharge were manually disassembled in a fume hood, and 100 waste positive electrode strips were removed.

[0074] (3) The discharged waste lithium battery positive electrode strips were sheared and crushed to obtain 1600g of crushed products;

[0075] (4) Under vacuum conditions, 200 Pa of carbon monoxide is introduced to form a low vacuum carbon monoxide atmosphere. In the pyrolysis furnace under the low vacuum carbon monoxide atmosphere, the crushed product in step (3) is heated to 400°C at a heating rate of 15°C / min, held for 40 min, and then heated to 900°C at a heating rate of 15°C / min. After holding for 50 min, the product is cooled to 35°C to complete the pyrolysis and obtain the pyrolysis product.

[0076] (5) The pyrolysis product described in step (4) is subjected to magnetic separation to obtain magnetically separated cobalt powder and non-magnetically separated lithium aluminate;

[0077] (6) The pyrolysis gas from step (4) is passed into a 1 mol / L calcium hydroxide solution to obtain a lithium-rich solution, wherein the lithium-rich solution is a lithium hydroxide-rich solution.

[0078] Example 3

[0079] This embodiment provides a method for targeted recycling of waste batteries, the method comprising the following steps:

[0080] (1) In order to ensure the safety of the experimental process, 100 waste lithium cobalt oxide mobile phone lithium batteries weighing about 2.5 kg were first discharged by physical short circuit for 12 hours, then immersed in 5% NaCl salt solution for full discharge for 48 hours, and then dried in a fume hood for 48 hours.

[0081] (2) The block-shaped waste lithium batteries after discharge were manually disassembled in a fume hood, and 100 waste positive electrode strips were removed.

[0082] (3) The discharged waste lithium battery positive electrode strips were sheared and crushed to obtain 1600g of crushed products;

[0083] (4) Under vacuum conditions, 200 Pa of carbon monoxide is introduced to form a low vacuum carbon monoxide atmosphere. In the pyrolysis furnace under the low vacuum carbon monoxide atmosphere, the crushed product in step (3) is heated to 600°C at a heating rate of 25°C / min, held for 20 min, and then heated to 700°C at a heating rate of 5°C / min. After holding for 70 min, the product is cooled to 20°C to complete the pyrolysis and obtain the pyrolysis product.

[0084] (5) The pyrolysis product described in step (4) is subjected to magnetic separation to obtain magnetically separated cobalt powder and non-magnetically separated lithium aluminate;

[0085] (6) The pyrolysis gas from step (4) is passed into a 1 mol / L calcium hydroxide solution to obtain a lithium-rich solution, wherein the lithium-rich solution is a lithium hydroxide-rich solution.

[0086] Example 4

[0087] This embodiment provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon monoxide at 10 Pa, the method is the same as that in Embodiment 1.

[0088] Example 5

[0089] This embodiment provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon monoxide at 100 Pa, the method is the same as that in Embodiment 1.

[0090] Example 6

[0091] This embodiment provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon monoxide at 500 Pa, the method is the same as that in Embodiment 1.

[0092] Example 7

[0093] This embodiment provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon monoxide at 800 Pa, the method is the same as that in Embodiment 1.

[0094] Example 8

[0095] This embodiment provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon monoxide at 1000 Pa, the method is the same as that in Embodiment 1.

[0096] Comparative Example 1

[0097] This comparative example provides a method for targeted recycling of waste batteries. Except for step (4) of introducing carbon dioxide at 200 Pa, the method is the same as that in Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a method for targeted recycling of waste batteries. Except for step (4) of introducing nitrogen gas at 200 Pa, the method is the same as that in Example 1.

[0100] The cobalt recovery rate, cobalt powder purity, lithium aluminate purity, and lithium concentration in the lithium-rich solution of the cobalt powder products obtained in the above examples and comparative examples are shown in the table below:

[0101] Table 1

[0102]

[0103]

[0104] As can be seen from Table 1:

[0105] As can be seen from Example 1 and Comparative Examples 1-2, the carbon monoxide atmosphere of the present invention can effectively recover cobalt metal powder and lithium aluminate, combined with Figure 2-4 It can be seen that the pyrolysis of the present invention can induce cobalt nanoparticles to aggregate against the carbon monoxide concentration gradient to form millimeter-sized large particles; as can be seen from Examples 1 and Examples 4-8, in the low vacuum carbon monoxide atmosphere of the present invention, the carbon monoxide pressure will affect the pyrolysis effect, thereby affecting the recovery effect.

[0106] In summary, this invention provides a method for targeted recycling of waste batteries. The method induces the directional transfer of solid oxygen in waste cathode materials through pyrolysis, forming a coexistence environment of cobalt and alumina, which effectively inhibits high-temperature alloying. At the same time, it utilizes the high-temperature complexation reaction between carbon monoxide and newly formed cobalt to induce cobalt nanoparticles to aggregate against the carbon monoxide concentration gradient, forming millimeter-sized large particles, thereby achieving magnetic separation and recycling.

[0107] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for targeted recycling of waste batteries, characterized in that, The method includes the following steps: (1) The positive electrode strip of the waste battery is crushed to obtain the crushed product; (2) Under a carbon monoxide atmosphere, the crushed product described in step (1) is pyrolyzed to obtain a pyrolysis product. Then, the pyrolysis product is magnetically separated to obtain a magnetically separated product, thereby realizing the recovery of valuable metals. (3) Pass the pyrolysis gas from step (2) into an alkaline solution to obtain a lithium-rich solution and realize lithium recovery; The reducing agent in step (2) of the pyrolysis includes the current collector of the positive electrode strip; The current collector is aluminum foil; The complexing agent used in step (2) for pyrolysis includes carbon monoxide.

2. The method according to claim 1, characterized in that, In step (2), the carbon monoxide atmosphere has a pressure of 10-800 Pa.

3. The method according to claim 2, characterized in that, In step (2), the carbon monoxide atmosphere has a pressure of 100-500 Pa.

4. The method according to claim 1, characterized in that, The carbon monoxide atmosphere in step (2) is a low-vacuum carbon monoxide atmosphere, which is formed by introducing carbon monoxide at 10-800 Pa under vacuum conditions.

5. The method according to claim 1, characterized in that, In step (2), the carbon monoxide atmosphere contains carbon monoxide gas from the pyrolysis gas of biomass.

6. The method according to claim 1, characterized in that, The pyrolysis in step (2) includes heating to a first temperature, then heating to a second temperature, and finally cooling down.

7. The method according to claim 6, characterized in that, The first temperature is 400-600℃, and the holding time at the first temperature is 20-40 minutes.

8. The method according to claim 6, characterized in that, The heating rate for a single heating cycle is 15-25℃ / min.

9. The method according to claim 6, characterized in that, The second temperature is 700-900℃, and the holding time at the second temperature is 50-70 minutes.

10. The method according to claim 6, characterized in that, The heating rate for the secondary heating is 5-15℃ / min.

11. The method according to claim 6, characterized in that, The temperature was lowered to 20-35℃.

12. The method according to claim 1, characterized in that, The magnetic separation products in step (2) include magnetically separated cobalt powder and non-magnetically separated lithium aluminate.

13. The method according to claim 1, characterized in that, The alkaline solution in step (3) includes a calcium hydroxide solution.

14. The method according to claim 1, characterized in that, The lithium concentration in the lithium-rich solution in step (3) is 5-10 g / L.

15. The method according to claim 1, characterized in that, In step (1), the waste battery is first physically short-circuited and discharged, then immersed in a salt solution for discharge, and finally dried and disassembled to obtain the positive electrode strip.

16. The method according to claim 1, characterized in that, The crushing method described in step (1) includes shear crushing.

17. The method according to claim 1, characterized in that, The waste batteries mentioned in step (1) include waste lithium cobalt oxide batteries.

18. The method according to claim 1, characterized in that, The method includes the following steps: (1) First, physically short-circuit and discharge the waste battery, then immerse it in a salt solution for discharge, and finally dry and disassemble it to obtain a positive electrode strip. Then, cut and crush the positive electrode strip to obtain the crushed product. (2) Under vacuum conditions, carbon monoxide at 10-800 Pa is introduced to form a low vacuum carbon monoxide atmosphere. Under the low vacuum carbon monoxide atmosphere, the crushed product in step (1) is heated to 400-600℃ at a heating rate of 15-25℃ / min, held for 20-40 min, and then heated to 700-900℃ at a heating rate of 5-15℃ / min, held for 50-70 min, and then cooled to 20-35℃ to complete the pyrolysis and obtain the pyrolysis product. (3) The pyrolysis product described in step (2) is subjected to magnetic separation to obtain magnetically separated cobalt powder and non-magnetically separated lithium aluminate; (4) Pass the pyrolysis gas from step (2) into a calcium hydroxide solution to obtain a lithium-rich solution with a lithium concentration of 5-10 g / L.

Images